Table of Contents

Introduction

This is an in-depth guide to AS Kog'Maw with a straight forward, from early to late game balanced item build.

Before I start, I feel that I have to clarify what the term "AS (short for Attack Speed) Kog'Maw" actually MEANS.
When you build attack speed you emphasise the damage comming from auto-attacks. Hence you want to buy items which help your auto-attacks in a way. Your auto-attacks are influenced by attack speed (AS) and attack damage (AD). However, increasing AS is much more beneficial than increasing AD for some reasons. An obvious one is that you'll apply more on-hit effects over time when you can attack more often.
So, while stacking AS, we notice that we get a lot of magical damage as bonus from items and the W-spell. That's the reason why AS Kog'Maw mostly (but not only) does MAGICAL damage, although he doesn't have much AP.

Pros / Cons

Pros
- anti-tank
- hybrid damage (about 3 physical damage : 4 magical damage)
- won't feed much when played well cause of his position in the back row
- it's just funny to watch people approach you in late game 1vs1, wading through your until they notice that they will be dead before actually reaching you and then try to get away and - of course - die

Cons
- very team dependant: you NEED someone between you and the enemy team. Two tanky champions in your team are better than one, only so much said. Kog'Maw is squishy as hell and can't run away when focused, so it doesn't matter how good you play Kog'Maw when you're simply doomed to be instant dead. Don't pick Kog'Maw when there are only squishies and a Malphite in your team

Abilities

Well, if you die, stick to a nearby enemy champion and BUUUUMM. If there are different choices take the one which will surely die when you explode, or one who will definitely getting even more harassed (hopefully to death) by your team mates in near future.

Your ult won't do as much damage as it would do with an AP build and you can't spam it too often without mana items. Use it to finish running enemies or to slightly harass and disturb them in the laning phase or before the teamfight has started, but DON'T spam it. Play AP if you want to do so.

Summoner Abilities

Ghost Exhaust
You don't have any escaping abilities besides your Void Ooze slow (which might not always be enough). Ghost out of ganks, ghost away from lost teamfights, ghost to teamfights if you are to far away from your team. Exhaust isn't that good, but if everything else fails, exhaust your chaser.

If you like Flash, take it instead of Exhaust. I NEVER got away with it, but well..if you can flash away through a wall..might be ok.
Another option I've used for a long time is Teleport, which makes up for your slowness. If you know that you are going to take mid, make sure to take this instead of Exhaust.

Greater Quintessence of Swiftness
x2 movement speed because Kog'Maw is slow and additional movement speed helps to survive ganks, keep up with the team/or the enemy or flee after a lost teamfight

Masteries

I'm, still experimenting with the new masteries. This is what I use atm, while buying Dorans blade as first item. You might want to take something else instead of Vampirism...Sunder for instance, or Veteran's Scars. Sadly the utility tree isn't worth points anymore.

Items

Start with a Doran's Shield or, if you lane together with a supporter, a Doran's Blade. That will save squishy Kog'Maw from being harassed to death throughout the laning phase. However, if things aren't going so well, and you have to return to base early, grab a(nother) Doran's Blade additionally.
Now we need Boots for slow Koggy and I recommend to buy Berserker's Greaves for now, cause you need the attack speed much more than anything else.
The next thing you want to have is [item=Malady]. Well, why not rushing Madred's Bloodrazor like many other guides recommend? It's simple as that: Madred's is build from Recurve Bow, which costs 1,050. Malady is build from two Daggers, which cost only 420 each. Means you can afford a Dagger when you couldn't afford a Recurve Bow, so it's easier to keep constantly going and doing well with your little monster.
After finishing Malady we want...more AS for sure. A good choice would be the rarely used Wit's End. It's cheap and does additional magic damage (which is even better; remember that we already do magic damage). Its passive, however, isn't so good on Kog'Maw since it doesn't burn mana anymore but gives magic resistance. However, the main reason for buing this item is the damage/AS and the fact that it's cheaper than Madred's. I haven't tried it, but I could imagine that Nashor's Tooth would be another great option for this slot if you don't have mana runes or feel that you need more mana.
If you haven't already done it, sell Doran's Blade again - you don't need it after the laning phase is over.
Now you should be a real threat to the other team. Guess what?! Finally you've got enough time to build your [item=Madred's Bloodrazor].
The last item is situational. Look at the enemy team! Is there any magic resistance ([item=Force of Nature] e.g.), build Void Staff for magic penetration. (With Malady, Nashor's and Void Staff you would have 150 AP from items. Even more threatening than with AS alone, eh?) If you like, you could also change your Boots to Sorcerer's Shoes for even more magic penetration.
If there isn't much magic resistance, build The Black Cleaver. I really like this item on Kog'Maw, because it provides AS (we are stacking that, right?), AD (not only more auto-attacks per second but also harder hitting ones, great!) and armor reduction (even harder hitting, harder hitting auto-attacks :p).
Of course you can also use this slot for a survivability item like Banshee's Veil or Guardian Angel, but that's very situational. Usually you don't need any defensive items besides Doran's Shield/Blade at the beginning, cause of your range and your ability to kill very quickly late game. One situation where you would want to buy Guardian Angel would be for instance when there's an enemy Katarina that flashes each teamfight in front of you (in the back line) and can't be stopped before her ulti has killed you. You are dead, but the rest of your team is still fine. Grab Guardians Angel in those cases to counter that Katarina. Get revived and shred her!
If the game is still going you might want to sell your Dorans Shield and replace it with whatever you haven't bought yet. You could have The Black Cleaver and Void Staff..muhahaha! Or go for Phantom Dancer and enjoy capped 2.5 attack speed if you decided not to sell Berserker's Greaves. Enemies will cry in fear when they see Kog'Maw the AS/Movement-Speedmonster approaching.

Annotation: If your team has many AP champions and many on the other team try to counter that with magic resistance, don't buy Void Staff. Instead ask your tank to buy Abyssal Scepter. This item lowers magic resistance but only in a range which is shorter than most of Kog'Maw's attacks. Your tank however will be in melee range most times and lower their resistance for you. Thank your tank and fire away!

Game is still running and you sold Doran's Shield:
[builder=Kog'Maw/ed21af3ae5fa04f53f64709551f050ef]

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If there is no heavy magic resistance:
[builder=Kog'Maw/818c5623f3940a068a9b0af32592a7b3]

Game is still running, you sold Doran's Shield and want capped AS:
[builder=Kog'Maw/37032f9c34d2102db4beb2c2eb45ff61]

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Example for a situational defensive build including Frozen Mallet (an item I usually don't get on Kog'Maw plus my reasoning why you might sometimes still want to buy it):

If you are facing a team full of squishy, very mobile gap-closers (Tryndamere, Twisted Fate, Katarina etc.), what might happen in solo queue, you shouldn't buy Madreds but Frozen Mallet to counter their mobility with the slow, and Guardians Angel to counter their gap-closing-abilities with the revive. Well, counter them, get fed and have enough money for Infitity Edge or any other really cool and expesive item to fill your last item slot:
[builder=Kog'Maw/8c1febf894449e60766643c9cf0e504d]

Skill Order

or simlpy said
R>W>Q>E

..but feel free to experiment here. Level what you need! Just make sure to take a point into your ult whenever possible.

- need to push back minion waves faster: level E
- need more range: level W
- need a lasthitting- and a harrassing tool against melees: level Q
- need nothing *lol*: level Q (for the AS-Buff) just because you have the time for it NOW

The Laning Phase

Playing side lane

When you arrive at your tower, stay there and don't try any heroic or brave moves. You are too squishy for such kind of things. Don't go for first blood in the bushes, it will probably be yours^^.
When the minions arrive, stay cautious! Only walk in when you know where your enemies are. When they have a jungler and there's only one enemy champion in your lane, check if there are two in the other lane to be sure that there IS only this single enemy.
Last hitting with Kog'Maw is quite hard in the beginning. (Even with .) Try it, but don't worry if it turns out to be not very successful. The key during the laning phase is to stay defensive. Don't use your spells until you have to. Harass when the enemy forces you to do so. For example when you are laning together with a melee champion the enemies will sooner or later try to focus him down when he gets to near. Your job then is to activate , harass as much as possible and help your mate to escape with a well placed . BUT never let the enemy minions focus you for longer than a few seconds. Otherwise it will happen that you find yourself as much harassed by the minions as you just harassed the enemy champion. Quite contra-productive, eh? In some games it's save enough to harass with , but it's quite risky because of its short range.
Beware of ganks! Wards come in very handy. Of course you can also check bushes with your ulti.
If your team decides to kill somebody (maybe someone from your team came to gank), do the obvious: move in range for while you wait for somebody to initiate. When the fight starts, cast your slow and hit . If needed finish with .
Hopefully you will destroy their turret before they destroy yours. Be very cautious while doing that. You're - as always - very vulnerable for ganks (coming from the river in this case). Better have your Ghost active.

Playing mid lane

If nobody else is there to cover mid, take it! But be careful, cause Kog'Maw is extremely vulnerable to faceroll-combos. Control your lane with and . Defend your turret and harass with these. Some players aren't very good in dodging your ult. If they go down on very low health, go in with and hope for a kill. (This won't happen each game, believe me.)
If your team doesn't have a jungler, you HAVE to do wraith and wolf camp from level 8 or 9 on whenever there's time for it. What's a carry without cash, eh? Because you will get more money from playing mid (and recall hopefully seldom) you may buy Madred's Bloodrazor earlier than I suggested above. You could skip Wit's End for instance. Sometimes I even go for Zeal very early, if I feel that I need the movement speed to dodge those faceroll-combos. After Madred's I build it into Phantom Dancer.

Farming

Once you got your ulti you've got an easy farming combo: on the minion casters --> --> wait until won't stack mana cost anymore and cast it again when you can be sure to last hit them with it (AP Kog'Maw can do this better, but well...)
Of course also use this on enemy minions while taking turrets down.

After the Laning Phase

When the first turrets are fallen, feel free to jungle a bit when there's nothing else to do. If nobody else claimes red or blue buff, take them. Blue will allow you to spam your ult. Red offers a nice slowing effect with your autoattacks resp. your . Watch your mini map for smouldering teamfights and make sure you attend^^. Help pushing lanes and destroying buildings (You can do both very well) but try not to do things on your own. You might win 1vs1, but 2 are usually too much. Check bushes with from a distance before you walk through or past.

Working in the Team

This is VERY important.

There is one rule: NEVER ever initiate a teamfight. I will explain to you why: Kog'Maw is especially in early-/mid-game only save in the back rows. You might think: "Well, I have . My increased range will keep me far enough away from any harm. Let's fire away!" That is wrong. When you initiate, your target is still flexible. Most likely it will simply back off. What will happen next is, that you move in a few steps closer to stay in range. That'll most likely be your death, because.."Uh, what happend? Where am I?"..you find yourself in the front row..or all alone in front of the front row^^. They'll target you. You have been slain!
It is far better to wait for your initiator and then fire away, because then the fronts are stable and you can be more or less sure that there will be something with a hard to chew down health bar between you and all those harm.
If a squishy or carry is in range, focus it, if not, well...you are an anti-tank...Kog'Maw does focus whom he pleases - to say it with Mundos words.
Try to hit fleeing ones with and hopefully your team will win the fight and you got a few kills more.
If you're losing for sure, help fleeing mates and yourself escaping with . If you're helping yourself with it, spill it in front of you and then escape by running over it, while your enemies will get slowed if they decide to follow you.

What to look out for

The biggest threat for Kog'Maw are champions who can close the gap between you and them, and ones who can stun you. (The more HP such a champion has the worse, cause then the chances are lower that you will be able to kill them before they kill you.)
Steer clear of Xin Zhao, Jax and Irelia because they can jump on you (Akali is dangerous too, but easier to kill). Kill them while they are focusing someone else. Don't let Blitzcrank grap you. Try not to fight Sion with his stun 1vs1, you'll probably lose. Malzahars ulti will kill you if you haven't got any resistance etc.
Koggy shouldn't walk around alone, simple as that. Especially not when your Ghost is on cooldown.

Another thing: If the enemy team has another Kog'Maw it is often better to build AP/Mana and ult the other one into pieces, especially when you're both on the same lane.

Closing Words

Thanks for reading my guide!

Mainly I wrote it because Kog'Maw is my main champion for a long time now and I've tried several builds on him until I came to this current AS build. AP is somehow more situational and I found AS much more reliable (if Kog'Maw fits in your team of course). Also I found that rushing Madred's is often not as good as many people/guides claim it to be. (Reason is stated in the "items section".) I hope this guide shows that you can also enjoy AS Koggy with a later Madred's. Another important thing is that many guides throw in some survivability Kog'Maw simply doesn't need. ( Frozen Mallet or an early Haunting Guise are just two of them.) Either Kog'Maw is in the back rows and wouldn't be hurt either way, or he is focused and will die no matter what. Don't buy those items just for their other effects, it will cost you precious AS.

If you have suggestions or questions, fire away! No need to wait for your initiator here ;)